In electrophotography, an electrophotographic substrate containing a photoconductive insulating layer on a conductive layer is imaged by first uniformly electrostatically charging a surface of the substrate. The substrate is then exposed to a pattern of activating electromagnetic radiation, such as, for example, light. The light or other electromagnetic radiation selectively dissipates the charge in illuminated areas of the photoconductive insulating layer while leaving behind an electrostatic latent image in non-illuminated areas of the photoconductive insulating layer. This electrostatic latent image is then developed to form a visible image by depositing finely divided electroscopic marking particles on the surface of the photoconductive insulating layer. The resulting visible image is then transferred from the electrophotographic substrate to a necessary member, such as, for example, an intermediate transfer member or a print substrate, such as paper. This image-developing process can be repeated as many times as necessary with reusable photoconductive insulating layers.
Image forming apparatus such as copiers, printers and facsimiles, including electrophotographic systems for charging, exposure, development, transfer, etc., using electrophotographic photoreceptors have been widely employed. In such image-forming apparatus, there are ever-increasing demands for improving the speed of the image-forming processes, improving image quality, miniaturizing and prolonging the life of the apparatus, reducing production and running costs, etc. Further, with recent advances in computers and communication technology, digital systems and color-image output systems have been applied also to image-forming apparatus.
Electrophotographic imaging members (i.e. photoreceptors) are well known. Photoreceptors having either a flexible belt or a rigid drum configuration are commonly used in electrophotographic processes. Photoreceptors may comprise a photoconductive layer including a single layer or composite layers. These photoreceptors take many different forms. For example, layered photo-responsive imaging members are known in the art. U.S. Pat. No. 4,265,990 to Stolka et al., which is incorporated herein by reference in its entirety, describes a layered photoreceptor having separate photo-generating and charge-transport layers. The photo-generating layer disclosed in the 990 patent is capable of photo-generating holes and injecting the photo-generated holes into the charge-transport layer. Thus, in the photoreceptors of the 990 patent, the photo-generating material generates electrons and holes when subjected to light.
More advanced photoconductive photoreceptors containing highly specialized component layers are also known. For example, multilayered photoreceptors may include one or more of a substrate, an undercoating layer, an intermediate layer, an optional hole- or charge-blocking layer, a charge-generating layer (including a photo-generating material in a binder) over an undercoating layer and/or a blocking layer, and a charge-transport layer (including a charge-transport material in a binder). Additional layers, such as one or more overcoat layer or layers, may be included as well.
In view of such a background, improvement in electrophotographic properties and durability, miniaturization, reduction in cost, etc., in photoreceptors have been studied, and photoreceptors using various materials, including cross-linked siloxane materials, have been proposed.
However, there are shortcomings associated with cross-linked siloxane-containing overcoat layers. In particular, electrical charges can migrate from the photoreceptor surface into the porous cross-linked siloxane-containing overcoat, and cause image problems. Another shortcoming associated with the siloxane-containing overcoat layers is the high torque required to rotate the coated photoreceptor against a cleaning blade. In addition, because the silicon hard overcoat layers are typically prepared by sol-gel processes, shrinkage of the applied layer occurs, which strains the resulting materials. Although attempts have been made to solve these problems by modifying various component materials, such modifications typically present trade-offs in terms of improving one property while deteriorating another property.
By providing an aromatic silicon-containing compound, which can be incorporated into new cross-linked siloxane-containing outmost protective layers such as for use in electrophotographic photoreceptors, these problems may be overcome. Such aromatic silicon-containing compound provides such benefits as high rigidity and good compatibility with hole transport molecules typically used in cross-linked siloxane-containing overcoat layers. Cross-linked siloxane-containing protective layers and electrophotographic photoreceptors formed using the aromatic silicon-containing compound in turn show improved micro-mechanical properties, such as low torque, higher wear resistance, and the like, and improved and sustained performance in deletion resistance.
However, use of such aromatic silicon-containing compounds in cross-linked siloxane-containing outermost protective layers has been limited by the methods used to prepare such compounds. Typically, useful aromatic silicon-containing compounds are prepared on a small scale, in processes that include difficult purification procedures. These processes have low yields of crude products that contain impurities and oligomers that must be removed by tedious, non-scalable purification procedures.
Thus, there still remains a need for improved methods for preparing aromatic silicon-containing compounds that will produce high yields of the desired aromatic silicon-containing compounds, and there remains a need for efficient, scalable methods for preparing the aromatic silicon-containing compounds.